1. Field of the Invention
The present invention relates generally to a safety belt retractor and, more particularly, to a safety belt locking device used with a safety belt retractor for locking the protraction of the safety belt when the vehicle suddenly stops.
2. Description of the Prior Art
Generally, vehicles such as automobiles or airplanes are provided at the seats with safety belt retractors for ensuring the safety of the passengers. Such vehicles meet a sudden fall of the vehicle velocity when they suddenly stop or clash with something in accident. In this case, an inertia forcebly moves the passengers forwardly to possibly clash with the handle or front glass. Thus, at this time, such a sudden velocity change must be simultaneously sensed for locking the violent forward movement of the passengers in order to avoid such a danger. Various locking devices have thus far developed. The present applicant has been proposed one of the conventional locking devices entitled "Belt Retractor" bearing Ser. No. 624,827. In this invention, the sudden change of the vehicle velocity is sensed by means of an inertia member, and then is transmitted to the clutch mechanism provided with another inertia member. With a temporary stop of the latter inertia member, the ratchet wheel interlocking with the safety belt is locked to prevent a sudden protraction of the safety belt. According to this invention, the protraction of the safety belt is reliably locked. The locking device of the invention, however, employs a complex mechanism for performing the locking function, and thus is problematic in cost and reliability.